1. Field of the Invention
The present invention relates to a dual network telephone device that is able to selectively perform telephone communication via a public telephone network and via an IP telephone network.
2. Description of the Related Art
EP0999683A2 discloses a telephone device (a facsimile device) that is configured to perform telephone communication via a public telephone network. This telephone device is configured from a base device and a plurality of handset devices. Further, International Publication No. WO 03/073714 discloses an IP telephone device that is configured to perform telephone communication via an IP telephone network. Furthermore, in order to perform telephone communication using the IP telephone device, it is necessary to register an IP address and IP telephone identification information (for example, a SIP URI) of this IP telephone device to an IP telephone server.
Software for carrying out IP telephone communication is required to perform a telephone communication via the IP telephone network. For example, in a case where a telephone device is configured from a base device with which one or more handset devices can be utilized together, since both the base device and handset devices function as IP telephone devices, it is conceivable that the above software is installed in both the base device and the handset devices. However, employing this configuration requires storage areas for storing the above software in both the base device and the handset devices, thereby increasing manufacturing costs.